This invention relates to a leak detection system programmable controller. More specifically, this invention is an improvement on U.S. Pat. Nos. 4,740,777 and 4,763,193 that are hereby incorporated by reference for a Programmable Fluid Detector.
U.S. Pat. Nos. 4,740,777 and 4,763,193 are directed to an electronic, microprocessor based, programmable hydrocarbon leak detection system controller (hereinafter controller) of the type typically used in vehicle service stations that dispense fuel. The controller is connected to various transducers or probes such as those that work on the principals of conduction to differentiate between water and hydrocarbon, probes that work on the principal of absorption to detect vapors, and pressure probes that work on the principal of pressure changes. These probes determine if liquid hydrocarbons are leaking from hydrocarbon tanks and lines. When the controller was designed, dispensing lines had line pressure probes, but the controller only annunciated when a gross or catastrophic leak occurred. The controller did not have the capability to indicate the line pressure probe had performed a line tightness test also known as a precision test.
Starting in 1990, the Environmental Protection Agency (E.P.A.) began requiring either an annual line tightness test or a monthly line tightness test with a required detection rate of "0.2 gallon [0.757 liters] per hour leak rate or a release of 150 gallons [567.81 liters] within a month with a probability of detection of 0.95 and a probability of false alarm of 0.05." 40 C.F.R. .sctn. 280.43 (h) (1) (1988).
The monthly line tightness test could be performed but required that product dispensing be halted during the test and experienced problems with false alarms, and lacked a positive output that the line tightness test was successful
Since the leak detection controller was not designed to process or report dispensing line pressure and status, the controller's software Error Check Routine as described in U.S. Pat. Nos. 4,740,777 and 4,835,717 was originally only programmed to respond to the statuses of oil, dry, or wet. If multiple statuses or no status was received by the controller from any probe, the controller would indicate an error condition. Therefore, for the leak detection controller to respond to a line pressure probe, without changing hardware, the pressure would have to report some combination of oil and dry rather than pressures.
What is needed is a software program improvement that will allow the controller to perform a monthly line tightness test with the a line pressure probes that reports the statuses of oil, dry, oil and dry, or no status. Additionally, a program modification is needed that will permit the controller to visually display the results of the line tightness test.